I. Field
The following description relates generally to wireless communications, and more particularly to supporting handoffs and multiple connections in a wireless communication system.
II. Background
Wireless communication systems are widely deployed to provide various types of communication; for instance, voice and/or data may be provided via such wireless communication systems. A typical wireless communication system, or network, can provide multiple users access to one or more shared resources. For instance, a system may use a variety of multiple access techniques such as Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), and others.
Common wireless communication systems employ one or more base stations that provide a coverage area. A typical base station can transmit multiple data streams for broadcast, multicast and/or unicast services, wherein a data stream may be a stream of data that can be of independent reception interest to a wireless terminal. A wireless terminal within the coverage area of such base station can be employed to receive one, more than one, or all the data streams carried by the composite stream. Likewise, a wireless terminal can transmit data to the base station or another wireless terminal.
Handoffs are commonly employed in wireless communications systems to transfer an ongoing communication session from one base station connected to a core network to a second base station connected to the core network. Oftentimes, hard handoffs may be employed where a wireless terminal may be connected to one base station at a time. Thus, to transition to a disparate base station, the wireless terminal drops a radio link for a period of time prior to connecting to the new base station (e.g., make before break).
Another conventional technique for handing off typically utilized in CDMA systems employs soft handoffs where a wireless terminal may be connected to several base stations simultaneously. The set of base stations to which the wireless terminal is connected in CDMA systems may be referred to as an active set for the wireless terminal. Conventionally, downlink soft handoffs oftentimes utilize simultaneous transmission to the wireless terminal from disparate base stations, which may be inefficient, since multiple copies of a signal may be transmitted to the wireless terminal. Further, multiple, redundant, over the air transmission may be particularly inefficient for higher bit rate signals related to IP data.